I used to do this for a living, the secret is VERY simple, but NOT many people
seem to understand the concept.
I use old copper house wire to make temporary bundle guides (like fishing rod
line guides), where the bundles should logically go. These are used to rough
route the wires.
Basically the key is to route wires first, cut them long (2-4 inches) but NOT
connect them. Then using masking tape, wire, string, etc. Make everything
look like you want. Tie it down, I use Adel clamps to connect to the airframe,
and waxed dacron lacing tape to bundle the wires. After the bundles are then
nice and neat. THEN terminate the ends and hook up the gear.
DO NOT hook up wires, and try to string them one by one, you will just end
up with a big mess. This is how most people make a mess in my opinion.
Regards,
Jeff Hays